#include <stdio.h>


int main()
{
    long a[50] = {0};
    //第50个月有多少对兔子
    a[0] = 1;
    a[1] = 1;
    for(int i = 2; i < 50;i++)
    {
        a[i] = a[i-1] + a[i-2];
    }
    printf("%ld\n",a[49]);
    return 0;
}